Cooking doneness or readiness refers to a status of food being cooked where a good balance of nutrition preservation and taste enhancement is reached. Both undercooking and overcooking give negative consequences in these two aspects, as well as food safety. Food that is undercooked may cause food-borne diseases on its consumers, for the temperature rise and/or its sustaining time are insufficient to kill harmful bacteria or parasites, especially in the inner part of the food. On the other hand, overcooking affects the food taste and texture, for instance due to excessive loss of moisture, and possibly destroys the structure of certain nutrients, which leads to the reduction of their health benefits.
Key to resolve this problem is to monitor core/inner temperature of food during cooking. For detecting core temperature of cooked food, people have been using a needle-shaped thermometer that is punched into the food to provide temperature measure where the needle tip is located. The method is, however, destructive and troublesome, still involving significant amount of manual work.
Other major thermal sensing methods include electromagnetic radiometry (at microwave or infrared range), magnetic resonance thermometry and ultrasound thermometry. These methods are non-destructive and some may sense the temperature a few centimeters deep into the object. However, they either require complex setup thus high cost, or are subject to various disturbing factors thus making the measurement unreliable.